I've been working on a simple mod of the dimmable led actuator available in the examples folder.

I needed a few things that were not included, like the ability to set a more precise fade level, make longer fades and also being able to change those fade times dynamically.

Also, as a result of longer dafe times, I had to modify the sketch so the node is still able to send/receive messages during fade time.

You could send messages from VERA this way:

luup.call_action("urn:upnp-arduino-cc:serviceId:arduino1", "SendCommand", {radioId="6;100", variableId="DIMMER", value="100,25"}, 130)

This message is sent to node id 6, with parent node id 130, and tells the node to fade to 100% in 25 seconds.
You could choose any number (0-100) to fade to, instead of the 10% increment Vera offers. Also the old functionality remains working as before.

Here's the sketch in case someone is interested:

/***
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 * 
 * DESCRIPTION
 * This sketch provides a Dimmable LED Light using PWM and based Henrik Ekblad 
 * <henrik.ekblad@gmail.com> Vera Arduino Sensor project.  
 * Developed by Bruce Lacey, inspired by Hek's MySensor's example sketches.
 * 
 * The circuit uses a MOSFET for Pulse-Wave-Modulation to dim the attached LED or LED strip.  
 * The MOSFET Gate pin is connected to Arduino pin 3 (LED_PIN), the MOSFET Drain pin is connected
 * to the LED negative terminal and the MOSFET Source pin is connected to ground.  
 *
 * This sketch is extensible to support more than one MOSFET/PWM dimmer per circuit.
 *
 * REVISION HISTORY
 * Version 1.0 - February 15, 2014 - Bruce Lacey
 * Version 1.1 - August 13, 2014 - Converted to 1.4 (hek) 
 * Version 1.2 - April 13, 2015 - Added long dynamic and precise fade, also made fade non exclusive (ferpando)
 ***/
 
 #include <Time.h> 
 
#define SN "DimmableLED"
#define SV "1.2"

#include <MySensor.h> 
#include <SPI.h>

#define LED_PIN 5      // Arduino pin attached to MOSFET Gate pin

MySensor gw(9,10);

static int currentLevel = 0;  // Current dim level...
static int requestedLevel = 0;

MyMessage dimmerMsg(0, V_DIMMER);
MyMessage lightMsg(0, V_LIGHT);

int FADE_DELAY;   // Delay in ms for each percentage fade up/down (10ms = 1s full-range dim)

/***
 * Dimmable LED initialization method
 */
void setup()  
{ 
  Serial.println( SN ); 
  gw.begin( incomingMessage );
  
  // Register the LED Dimmable Light with the gateway
  gw.present( 0, S_DIMMER );
  
  gw.sendSketchInfo(SN, SV);
  // Pull the gateway's current dim level - restore light level upon sendor node power-up
  gw.request( 0, V_DIMMER );

}

/***
 *  Dimmable LED main processing loop 
 */
void loop() 
{
  gw.process();
  fadeToLevel();
  // if delay is too long, it might stop the node from receiving/sending more messages for a long time.
  //doing it this way, the node can keep functioning regardless fade completition.
}

void incomingMessage(const MyMessage &message) {
  if (message.type == V_LIGHT || message.type == V_DIMMER) {
    
    if(message.sensor == 100 ){ //fade special, addressed to node 100
      // Message payload: value to fade to, seconds to fade     example: "20,10"
      
      int commaIndex = msg.indexOf(',');

      String firstValue = msg.substring(0, commaIndex);
      String secondValue = msg.substring(commaIndex+1);

      requestedLevel=firstValue.toInt();
      int steps=abs(currentLevel-requestedLevel);

      if(commaIndex == -1){
         FADE_DELAY=10;
      }else { 
         FADE_DELAY = 1000* secondValue.toInt() / steps;
      }
    }else { //fade normal
    
          FADE_DELAY=10;
          //  Retrieve the power or dim level from the incoming request message
          requestedLevel = atoi( message.data );
          
          // Adjust incoming level if this is a V_LIGHT variable update [0 == off, 1 == on]
          requestedLevel *= ( message.type == V_LIGHT ? 100 : 1 );
          
          // Clip incoming level to valid range of 0 to 100
          requestedLevel = requestedLevel > 100 ? 100 : requestedLevel;
          requestedLevel = requestedLevel < 0   ? 0   : requestedLevel;
          
          }
       
      Serial.print( "Changing level to " );
      Serial.print( requestedLevel );
      Serial.print( ", from " ); 
      Serial.println( currentLevel ); 
       
         
      // Inform the gateway of the current DimmableLED's SwitchPower1 and LoadLevelStatus value...
      gw.send(lightMsg.set(currentLevel > 0 ? 1 : 0));
  
      // hek comment: Is this really nessesary?
      gw.send( dimmerMsg.set(currentLevel) );
    
    }
}

/***
 *  This method provides a graceful fade up/down effect
 */
void fadeToLevel() {

  if ( currentLevel != requestedLevel ) {
    int delta = ( requestedLevel - currentLevel ) < 0 ? -1 : 1;
  
    currentLevel += delta;
    Serial.print( "analog write: " );
    Serial.println( currentLevel / 100. * 255 );
    analogWrite( LED_PIN, (int)(currentLevel / 100. * 255) );
    delay( FADE_DELAY );
  }
  
}